Page:Philosophical Transactions - Volume 005.djvu/45

 dle; but he alwayes found the same quantity of Declination West-ward.

But by the Observations, here made formerly, it appears, that the Needle hath declin'd East-ward to 8 degrees, and hath afterwards been diminishing, until 'tis come to the other part, where we find it at present. The Observations, that may be made hereafter, will shew how far the Declination will advance towards the West, and what will happen after its greatest elongation; it not being probable, it should encrease alwayes, and make a whole turn.

It seems not, that this difference of ten degrees and more can be attributed to the change of the Pole of the Earth, as some esteem'd, perhaps before they knew it was so great; nor (as others would have it) to the Magnet, or to the Iron, that are found in certain places, because there is but little Load-stone; and Mr. Auzout affirms, that the Mines, which he hath seen, make no impression at all on the Needle. So that 'tis difficult to hit the true cause of such a Variation: Yet however, if the direction of the Magnet, and of the Needle touched by it, depends from the flux of a certain matter, passing through the whole Earth, or the exterior parts of it, strait along the Axis; it may be said, that it proceeds from changes made in the said flux, which, supposing the inequalities of the Earth, and the alterations continually made therein, as well artificial, by excavations such like other works, as Natural, by corrosions caused by fire and water, or by the generation of Metta's and Stones (besides the various changes, we cannot think of by reason of the little knowledge we have of so vast a Body as the Earth) cannot but in progress of time change its scituation. To illustrate this with an Example taken from Rivers; They, although they were running strait, cannot remain long without winding, and changing their course, if it happen, that the ground, over which they run, be unequal, or of a different nature. So 'tis probable, that the inequalities of the Earth may in time occasion some bending in the current of this Magnetick matter, and make it change its bed and channel: Whence it comes to pass, that the Needle changeth its direction according as the Current changeth, which directs it. And if you will consider the variety of